In fuel-air explosive (FAE) devices a burster functions to burst a container for a liquid fuel and that fuel is disseminated in air to form a cloud of fuel. At a subsequent time a cloud detonator detonates the cloud.
The FAE device of this invention is a particularly effective aerial weapon because the burster is positioned below the fuel level and the detonator is positioned at the upper level of the fuel, providing both blast and burning effects upon targets. Good efficiency per unit weight is obtained since only fuel is carried to the target and the ambient air comprises the oxidizer for the fuel. In such a weapon the fuel is explosively disseminated in a cloud which is detonated to provide destructive forces. Detonation of the mixture of fuel and air provides a blast effect and the combustion provides a flame which produces substantial damage.
The explosive charge is constituted of volatile hydrocarbons which:
do not require oxygen for spontaneous combustion (e.g. ethylene oxide, propylene oxide);
continue to burn without oxygen or air (e.g. propyl nitrate);
contain a high proportion of oxygen and cause a violent reaction on contact with combustible material (e.g. acetic peroxide);
explode on contact with moist air at ambient temperature (e.g. diborane);
react violently on contact with oxygen-rich materials and, in addition, ignite spontaneously on contact with certain substances.
In order to obtain maximum effectiveness of such weapons against most surface targets, it is desirable to disperse the fuel in a substantially pancake-shaped cloud within a few feet of the ground. It is found that since targets, such as personnel, vehicles and the like, are located at ground level, fuel disseminated at higher elevation is reacted and dissipated with little, if any, effect upon a target. In order to obtain pancake-shaped clouds of fuel an implosive technique has been devised for very rapid radial dissemination with minimized vertical displacement of the fuel. It is found with such weapons, however, when delivered from aircraft or the like so that the impacting weapon has a substantial vertical velocity, that the pancake-shaped cloud of disseminating fuel retains a vertical velocity component from the original falling weapon and is thereby driven into the ground at a range short of the maximum range obtainable.
Orientation of the cloud has also been a problem for FAE explosives. It is especially a problem when the charge must go off in contact with the ground. This problem might be attributed to the conventional burster configuration. The conventional burster is a central cylinder of high energy explosive which disperses the fuel radially when detonated. The fuel surrounds this explosive core in a cylindrical shape. The result is a burst pattern which resembles a donut; it has a hole in the center due to the explosive burster and is somewhat flat due to the lack of fuel dispersed in any other direction besides radial. This radial burst pattern acts detrimentally when the burster is not perpendicular to the ground orientation. One solution is to move away from the current configuration, to the more practical solution provided by this invention.
In an attempt to invent a FAE weapon which can be used as a demolition charge, the problems with ground effects have been addressed by moving towards more practical configurations for hand placed charges. One concept is to use the possible gains in blast effects of a hemispherical cloud by configuring the device like a hemisphere. This means that the burster is shaped like a hemisphere and the fuel surrounding the burster is hemispherically shaped too. Another concept might be to make the configuration spherical, using a spherical cannister for the fuel and a ball shaped burster. These configurations have some merit, but still must be placed to give the burster proper orientation with respect to the ground.